Clad alloy substrates and method for making same

ABSTRACT

A method for producing a single-clad or multiple-clad product includes providing a welded assembly comprising a cladding material disposed on a substrate material. Both the substrate material and the cladding material are individually selected alloys. At least a first edge of the cladding material of the welded assembly does not extend to a first edge of the substrate material and thereby provides a margin between the first edges. A material that is an alloy having hot strength greater than the cladding material is within the margin and adjacent the first edge of the cladding material. The welded assembly is hot rolled to provide a hot rolled band, and the material within the margin inhibits the cladding material from spreading beyond the edge of the substrate material during the hot rolling. In certain embodiments of the methods, the substrate material is stainless steel and the cladding material is nickel or a nickel alloy.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation application claiming priority under35 U.S.C. §120 to co-pending U.S. patent application Ser. No.10/865,060, entitled, “CLAD ALLOY SUBSTRATES AND METHOD FOR MAKINGSAME”, filed Jun. 10, 2004, which is hereby incorporated by referenceherein in its entirety.

BACKGROUND OF THE TECHNOLOGY

1. Field of Technology

The present disclosure relates to clad alloy substrates and to methodsof making such clad materials. The present disclosure also relates toarticles of manufacture made from or including clad alloy substrates andto methods of making such articles of manufacture.

2. Description of the Background of the Technology

In certain applications requiring a material combining high strengthwith corrosion resistance, clad alloys are used. One common example of aclad alloy exhibiting favorable strength and corrosion resistanceincludes a stainless steel layer clad on its opposed surfaces with alayer of nickel or a nickel-base alloy (i.e., an alloy that ispredominantly composed of nickel). Applications in which such cladmaterials are used include chemical cisterns, chimney flues, batteries,tubing, heat exchangers, piping for oil and gas, tanks for chemicals,and cookware. The stainless steel layer provides relatively highstrength, while the nickel or nickel-base cladding layers resistcorrosion under demanding conditions. Using a nickel dual-clad stainlesssteel of this type also has the advantage that the composite material isless expensive than certain high alloy content superaustenitic stainlesssteels and nickel-base alloys providing similar corrosion resistanceproperties.

The cladding process involves cladding a substrate material with eithera single cladding layer or with a cladding layer on each of thesubstrate's opposed surfaces. The process used to produce a clad alloymust bond the one (single-clad) or two (dual-clad) cladding layers tothe substrate sufficiently to prevent delamination of the claddinglayers while under service conditions. Several cladding methods areknown.

One known method for producing a clad stainless steel is described inU.S. Pat. No. 4,936,504. More specifically, the '504 patent describesmethods for cladding stainless steel with various materials includingcopper, nickel and invar (an iron-36% nickel alloy). In general, the'504 patent describes a method wherein sheets of the stainless steelsubstrate and the cladding materials are stacked together and thenrolled into a tight coil. The coil is heated in a vacuum furnace at hightemperature for an extended period, thereby diffusion bonding the sheetsof cladding materials to the stainless steel sheets. Significant energyis required to operate the vacuum furnace equipment and maintain thecoil at elevated temperature for an extended period when conducting the'504 patent's method, and this adds substantially to the cost of thefinished clad material.

U.S. Pat. No. 5,183,198, describes a method for producing a clad steelplate wherein a stainless steel or nickel alloy is clad onto aniron-base substrate comprising 0.020 to 0.06% carbon, 0.5% or lesssilicon, 1.0 to 1.8% manganese, 0.03% or less phosphorus, 0.005% or lesssulfur, 0.08 to 0.15% niobium, 0.005 to 0.03% titanium, 0.05% or lessaluminum and 0.002 to 0.006% nitrogen. (All percentages herein areweight percentages unless otherwise indicated.) Slabs of the claddingmaterial and the substrate material are rolled to plates of prescribedthickness. After smoothing, cleaning and degreasing all contact surfacesof the plates, an assembly slab is prepared by sandwiching a plate ofthe iron-base substrate material between two plates of the claddingmaterial. The periphery of the assembled plates is then seal-welded anda vacuum pump used to remove air between the plate's contact surfaces.The assembly slab is then heated in the range of 1100° to 1250° F. andsubjected to one or more rolling and cooling steps to adhere thematerials and form the clad product. As such, in contrast to the methodof the '504 patent, which utilizes a vacuum furnace, the '198 patentteaches creating a vacuum only in the space between the opposed surfacesof the cladding material and the substrate material.

In yet another known method for producing clad materials, known asexplosion cladding, the controlled energy of a detonating explosive isused to create a metallurgical bond between two or more similar ordissimilar materials. Explosion cladding is a cold pressure process inwhich contaminant surface films on the materials to be bonded areplastically jetted off the base metals as a result of a high-pressurecollision of the two metals. During the high velocity collision of metalplates, a jet is formed between the plates, and contaminant surfacefilms that are detrimental to establishing a metallurgical bond areswept away in the jet. The metal plates, cleaned of surface films by thejet action, are joined at an internal point under influence of the veryhigh pressure that is obtained near the collision point. Early patentissued in this area include U.S. Pat. Nos. 3,233,312, 3,397,444 and3,493,353.

Each of the above known cladding methods requires the use of vacuumapparatus or other sophisticated equipment. In addition, the claddingmethod of the '504 patent, for example, is limited to the production ofrelatively thin gauge coil product and requires separately hot and coldrolling the substrate and cladding materials to sheet form before thecladding operation. With respect to explosive cladding, the process istypically expensive and labor-intensive, requires the use of dangerousexplosive materials, and may result in a non-uniform, wavy interfacebetween the substrate and cladding layers, which may be unsuitable forcertain applications.

Accordingly, it would be advantageous to provide an alternative methodfor cladding stainless steels and other materials with alloy claddingmaterials. Such alternative method preferably does not require use of avacuum furnace, explosive cladding equipment, or other sophisticatedproduction equipment.

SUMMARY

One aspect of the present disclosure is directed to a novel method forproducing a clad product from a substrate material and a claddingmaterial, wherein both the substrate material and the cladding materialare alloys. The method includes assembling the substrate and claddingmaterials and welding them together to provide what is referred toherein as a “welded assembly”, and then hot rolling the welded assemblyto provide a hot rolled band. The welded assembly may be provided bydisposing the cladding material on the substrate material so that atleast a first edge of the cladding material does not extend to a firstedge of the substrate material, thereby providing a margin between theadjacent first edges. An alloy having hot strength greater than thecladding material is disposed within the margin and adjacent the firstedge of the cladding material. The material disposed in the margininhibits the cladding material from spreading beyond the substratematerial during the hot rolling operation.

In certain embodiments of the foregoing method of the presentdisclosure, the cladding material and the substrate material are presentin the welded assembly in the form of individual plates, and the marginis defined by the space between a first edge of the plate of thecladding material and an adjacent first edge of the plate of thesubstrate material. In certain of such embodiments, the material havinggreater hot strength than the cladding material is the substratematerial itself and, in such a case the plate of the cladding materialis disposed in a recess formed in a surface of the plate of thesubstrate material so that a projecting portion of the substratematerial defines at least one wall of the recess and is within themargin and adjacent at least the first edge of the plate of the claddingmaterial. The recess may be formed in a surface of the plate of thesubstrate material using any conventional technique such as, forexample, casting the plate to include the recess or by removing materialfrom the plate surface, such as by machining.

In certain other embodiments of the method of the present disclosure, atleast one framing element composed of an alloy having hot strength lessthan the cladding material is positioned on the plate of the substratematerial adjacent the first edge of the plate of the cladding materialin the margin between such first edge and the first edge of the plate ofthe substrate material.

It is believed that the method of the present disclosure may be usedwith a wide range of combinations of substrate materials and claddingmaterials. As non-limiting examples, the substrate material may bestainless steel (such as T-316L stainless steel) or carbon steel.

In general, useful cladding materials must not be molten at the hotworking temperatures, and preferably also have a capacity for hotworking similar to the substrate material in the hot rolling temperaturerange. Non-limiting examples of possible cladding materials includenickel (which may include residual impurities), nickel-base alloys,stainless steels, and copper and copper alloys. The possible nickelcladding materials include the commercially pure wrought nickelsclassified under UNS Designation N02200 and UNS Designation N02201,which are available from Allegheny Ludlum, Pittsburgh Pa., as AL 200™alloy and AL 201™ alloy, respectively. These nickels differ only interms of the maximum carbon level allowed by the specifications, 0.15weight percent carbon for AL 200™ alloy, and 0.02 weight percent carbonfor AL 201™ alloy. In addition, each of the two nickels has thefollowing typical composition, in weight percentages: 0.02 copper, 0.05iron, 0.02 manganese, 0.05 silicon, 0.002 sulfur and balancenickel+cobalt.

Certain embodiments of the method of the present disclosure may furtherinclude the steps of annealing the hot rolled band formed on hot rollingthe welded assembly, and cold rolling the hot rolled band to provide aclad strip having a desired gauge. In certain embodiments, cold rollingthe hot rolled band may include two or more distinct steps of coldrolling, and the cold rolled strip also may be intermediate annealedbetween successive cold rolling steps so as to relieve stresses withinthe material. The one or more annealing steps may be, for example,conventional annealing or bright annealing. Other steps may be performedas are known in the metallurgical arts to provide the clad strip in adesired form and with desired characteristics.

In those embodiments of the method of the present disclosure wherein thematerial in the margin is not a projecting portion of the substratematerial, the framing material provided in the margin can be composed ofany alloy having hot strength greater than the cladding material andwhich is suitable for the processing steps applied to the weldedassembly. For example, when applying an embodiment of the method of thepresent invention to a substrate composed of a T-316L stainless steeland a nickel cladding material, the framing material may be T-304Lstainless steel. In certain embodiments of the method of the presentdisclosure, the welds of the welded assembly are such that asubstantially airtight space is provided between the cladding materialand the substrate material in the welded assembly. In such case themethod may include, prior to the step of hot rolling the weldedassembly, the step of evacuating air from the airtight space between thecladding material and the substrate material.

The method of the present disclosure is useful for providing single-clador multiple-clad substrate materials. One non-limiting application ofthe method will be for the production of dual-clad products, wherein thecladding layers may be the same or different materials. The clad productcan be designed to exhibit advantageous properties contributed by thesubstrate material and the one or more cladding materials. For example,a nickel dual-clad stainless steel strip may exhibit the superiorstrength properties contributed by the stainless steel core material andthe superior corrosion resistance properties contributed by the nickelcladding layers.

An additional aspect of the present disclosure is directed to a novelmethod for producing a clad stainless steel, wherein the methodcomprises hot rolling a welded assembly to provide a hot rolled band.The welded assembly is provided by disposing a plate of an alloycladding material on a stainless steel plate, wherein at least a firstedge of the plate of the cladding material does not extend to a firstedge of the stainless steel plate and thereby provides a margin on thestainless steel plate. At least one framing element is provided in themargin, adjacent the first edge of the plate of the cladding material,and the plate of cladding material and the stainless steel plate arewelded to the framing element. The framing element is an alloy havinghot strength greater than the cladding material. During hot rolling, theframing element inhibits the cladding material from spreading beyond thestainless steel. The method optionally further comprises annealing thehot rolled band, and cold rolling the hot rolled band, in one ormultiple stages, to provide a clad strip having a desired gauge.

The stainless steel plate and the plate of cladding material may becomposed of any suitable stainless steel type. As non-limiting examples,and, as noted with respect to embodiments discussed above, the stainlesssteel plate may be composed of T-316L, T-316, T-304L, or T-304 stainlesssteel, or any other austenitic stainless steel, and the claddingmaterial may be nickel, a nickel alloy, copper, a copper alloy or astainless steel. The framing element material is selected, in part,based on the requisite hot strength needed in light of the hot strengthof the cladding material. Non-limiting examples of possible framingelement materials include T-316L stainless steel, T-304 stainless steel,or any austenitic stainless steel, nickel-base superalloys, andcobalt-base superalloys. More generally, suitable framing materialsinclude those that have hot strength greater than the cladding material,that can be hot worked at the hot rolling temperatures employed, andthat have coefficient of thermal expansion similar to the othermaterials in the welded assembly so that significant stresses do notoccur and result in weld failure.

In certain embodiments, the plate of the cladding material has a lengthand a width, respectively, that are less than a length and a width ofthe plate of the substrate material. The plate of the cladding materialis disposed on a surface of the stainless steel plate so that the plateof the cladding material is spaced from the edges of the stainless steelplate and so that a margin extends around the entire periphery of thestainless steel plate. One or more framing elements are disposed in themargin around the entire periphery of the plate of the claddingmaterial.

As noted above, the method of the present disclosure may be applied forproducing multiple-clad products, such as dual-clad products. In thecase where the product is a dual-clad product, the welded assembly maybe provided by disposing a plate of an alloy cladding material on eachof the opposed surfaces of plate of a substrate material, such as astainless steel. The plates are arranged so that at least a first edgeof each of the plates of the cladding material does not extend to afirst edge of the stainless steel plate and thereby provides a margin oneach of the opposed surfaces of the stainless steel plate. At least oneframing element composed of an alloy having hot strength greater thanthe cladding material is provided in the margin and adjacent the firstedge of each plate of cladding material. Each plate of cladding materialand the stainless steel plate are welded to the framing elements.

Yet another aspect of the present disclosure is directed to a method forproducing a clad stainless steel wherein the method includes hot rollinga welded assembly to provide a hot rolled band. The welded assemblyincludes a stainless steel plate welded to a plate of a claddingmaterial that is an alloy. The plate of cladding material is disposed ina recess on a surface of the stainless steel plate such that aprojecting portion of the stainless steel plate defines the recess andsurrounds the peripheral edge of the plate of cladding material. Theprojecting portion of the stainless steel plate inhibits the claddingmaterial from spreading beyond an edge of the stainless steel during thehot rolling. The method optionally further includes annealing the hotrolled band, and cold rolling the hot rolled band to a clad strip havinga desired gauge. In those embodiments wherein the method is applied toproduce a dual-clad product, the welded assembly includes two plates ofan alloy cladding material. Each plate of cladding material is disposedin a recess on each of the opposed surfaces of the stainless steel platesuch that a projecting portion of the stainless steel plate on eachopposed surface of the stainless steel plate defines the recess on theparticular surface of the stainless steel plate and surrounds aperipheral edge of the plate of cladding material disposed in therecess.

A further aspect of the present disclosure is directed to a method ofmaking a dual clad stainless steel strip. The method includes providinga welded assembly by a process including disposing a plate of a claddingmaterial selected from nickel and a nickel alloy within a recess on eachopposed surface of a stainless steel plate so that a projecting marginon each opposed surface of the stainless steel plate defines the recesson that surface and surrounds the peripheral edge of the plate ofcladding material within the recess. Each plate of the cladding materialis welded to the adjacent projecting margin of the stainless steelplate. The welded assembly is hot rolled to a hot rolled band, and theprojecting margin of the stainless steel plate inhibits the claddingmaterial within a recess from spreading beyond the stainless steelduring the hot rolling. The hot rolled band subsequently may be coldrolled to a desired gauge.

The present disclosure is additionally directed methods of makingarticles of manufacture including providing a clad product by any of thenovel methods described in the present disclosure, and fabricating theclad product into the article of manufacture. Articles of manufacturethat may be made by such methods include, for example, chemicalcisterns, chimney flues, batteries, tubing, heat exchangers, piping foroil and gas, tanks for chemicals, and cookware.

Yet an additional aspect of the present disclosure is directed to weldedassemblies made as described in the present disclosure and which areuseful for making clad products.

The novel methods of the present disclosure for providing clad strip andother clad products do not require the use of a vacuum furnace orexplosive cladding equipment. As such, the present methods offeradvantages in terms of complexity and cost relative to the prior artprocesses described in the background section above.

The reader will appreciate the foregoing details and advantages of thepresent disclosure, as well as others, upon consideration of thefollowing detailed description of embodiments. The reader also maycomprehend additional details and advantages of the present disclosureupon making and/or using the method and/or the apparatus set forth inthe disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is diagram of one embodiment of the method for producing a cladproduct of the present disclosure.

FIG. 2 is a schematic perspective view of one embodiment of a weldedassembly according to the present disclosure wherein the assemblyincludes a plate of a substrate material, plates of a cladding material,and a plurality of framing elements.

FIG. 3 is a schematic top view of another embodiment of a weldedassembly according to the present disclosure wherein the assemblyincludes a plate of a substrate material that has been machined toinclude a recess and marginal frame, and wherein a plate of a claddingmaterial is disposed in the recess.

FIG. 4 is a schematic cross-sectional view taken at Y-Y through theassembly of FIG. 3.

FIG. 5 is a schematic cross-sectional view taken at X-X through theassembly of FIG. 2 after hot rolling to a gauge suitable for coldrolling.

FIG. 6 is a schematic cross-sectional view taken at Y-Y through theassembly of FIG. 3 after hot rolling to a gauge suitable for coldrolling.

FIG. 7 is a schematic end view of the hot rolled welded assembly of FIG.5 after trimming of the edges including the welds and framing elements.

FIG. 8 is a schematic cross-sectional view of a final clad product madeby the embodiment of FIG. 1.

FIG. 9 is a photograph of an embodiment of an assembly constructedaccording to an embodiment of the method of the present disclosure.

FIG. 10 is a photograph of the assembly of FIG. 9 wherein the elementsof the assembly have been welded together to provide a welded assembly,

FIGS. 11( a) and (b) are micrographs of an interface region of thebonded substrate and cladding layers of the welded assembly of FIG. 10after hot rolling.

FIG. 12 is a photograph of a section of a hot rolled band produced by anembodiment of the method of the present disclosure.

FIG. 13 is a photograph of another embodiment of an assembly constructedaccording to an embodiment of the method of the present disclosure.

FIG. 14 is a photograph of the assembly of FIG. 13 wherein the elementsof the assembly have been welded together to provide a welded assembly.

FIG. 15 is an additional embodiment of a welded assembly constructedaccording to an embodiment of the method of the present disclosure.

FIG. 16 is a schematic view of one embodiment of a core plate for anassembly according the present disclosure.

DETAILED DESCRIPTION

Embodiments of the invention of the present disclosure relate to methodsfor cladding one or more surfaces of an alloy substrate with an alloycladding material. The invention of the present disclosure isparticularly useful when the one or more cladding materials have lowerhot-strength than the substrate material.

Embodiments of the present method may be performed using welding, hotrolling, cold rolling and annealing techniques and equipment known tothose having ordinary skill in the metallurgical arts, but the methodincludes features not heretofore used to produce clad alloys. Forexample, such embodiments employ novel techniques to contain the spreadof lower hot-strength cladding materials during hot rolling.

As further described below, certain embodiments of the method of thepresent disclosure involve providing a welded assembly including platesof the substrate and cladding materials such that the one or more platesof the cladding material are “framed” with a material having higherhot-strength than the cladding material. The welded assembly is thensubjected to a suitable combination of processing steps, including hotrolling, cold rolling and, optionally, annealing, to bond the claddingmaterial to the substrate material and obtain the desired dimensions andmetallurgical and mechanical properties in the clad product. During hotrolling, material framing the cladding material inhibit the claddingmaterial from spreading beyond the substrate material, therebymaintaining the cladding material in the proper locations andmaintaining the desired range of material thickness during hot rolling.Thus, suitably framing the cladding material about the substratematerial may provide a high level of dimensional control so that thefinal clad product meets required dimensional characteristics.

As used herein, “alloy” means pure metals and metals includingincidental impurities and/or purposeful additions of metals and/ornon-metals.

As used herein, “plate” means a structure having a generally polygonalor rectilinear perimeter, having length and width dimensions, andincluding a relatively small thickness dimension.

As used herein, “hot strength” means the yield strength of a material athot rolling temperatures (for example, typically 1700 to 2400° F. forrolling nickel-clad stainless steel).

One embodiment of the method of the present invention includes the stepsgenerally shown in FIG. 1. Those steps are (1) providing a weldedassembly” suitable to produce the desired clad product; (2) compressingthe clad pack by rolling the pack at elevated temperature to bond (clad)the various plates in the clad pack at their interfaces; (3) reducingthe thickness of intermediate gauge clad material to a final desiredgauge; and, optionally, (4) annealing the product to achieve desiredmetallurgical and mechanical properties. These steps are furtherdescribed below.

In the first step of the method of FIG. 1, a plate or other shape of thealloy to be clad and one or more plates or other shapes of the claddingmaterial (the cladding material plates/shapes may be of the same ordifferent materials) are assembled and welded to form a stackedarrangement, which is then welded together. Such a welded arrangement isreferred to herein as a “welded assembly” for ease of reference. Forexample, as shown in FIG. 2, in one embodiment of the present disclosurefor producing a double-clad nickel/stainless steel/nickel product,assembly 10 is formed by positioning a plate 12 composed of Type 316Lstainless steel (UNS S31603) (“T-316L”) between a first thinner gaugeplate 14 of Type 201 nickel (UNS N02201) and a second identical plate(not shown). The length (“L”) and width (“W”) face dimensions of thenickel plates 14 are less than the corresponding dimensions of thestainless steel plate 12 so that a “frame” composed of several lengthsof Type 304 stainless steel (UNS S30400) (“T-304”) bar stock 16 can beplaced around each nickel plate 14. The framing material has a hotstrength that is greater than the hot strength of the cladding material.The stainless steel bar stock 16 has generally the same thickness as thenickel plates 14, is placed directly against each of the four edges ofthe nickel plates 14 and rests directly on the opposed surfaces of thestainless steel plate 12. The individual bar stock 16 elements arechosen so that their outer edges line up substantially flush with theouter edge of the stainless steel plate 12. The bar stock 16 width ischosen so that the hot strength of the framing material is greater thanthe hot strength of the nickel cladding material and contains the softernickel material during hot processing.

After the various elements of the assembly 10 are assembled, theassembly is arc welded together completely around the two exposed seamson each side of the pack using stainless steel welding filler metal. Afirst seam 20, between a nickel plate 14 and the surrounding stainlesssteel bar stock 16, is identically present on both sides of the cladpack 10 (one side shown in FIG. 2). A second seam 22, which is theperipheral seam between the stainless steel plate 12 and the stainlesssteel bar 16, also is identically present on both sides of the cladpack. FIG. 2 schematically depicts a butt weld joint with a squaregroove for each of these seams. As is known in the art, bevels also maybe machined or otherwise formed on the edges of the elements to bewelded to aid in obtaining the appropriate penetration of the weldmetal. Also, although particular manner or manners of welding theassembly is described in connection with the present embodiment, anysuitable manner of welding together the various elements of an assemblymay be used. For example, in certain embodiments a discontinuous weldmay be used to connect one element of the assembly to another assembly,which may reduce expense associated with the welding step.

Once welded in place, the stainless steel bar stock 16 forming theframing inhibits the relatively lower hot-strength nickel claddingmaterial from spreading beyond the stainless steel substrate materialduring hot rolling. This aids in positioning the cladding material atthe proper locations and in maintaining the desired ratio of thicknessof the stainless steel core layer and nickel cladding layers throughoutthe production process. Although in this example the framing elementsare in the form of stainless steel bar stock, it will be understood thatthe framing elements may be of any alternate material having hotstrength greater than the nickel cladding material and that is suitableto inhibit the cladding material from spreading beyond the substratematerial during hot rolling.

FIG. 3 schematically depicts a top view of one alternate construction ofa welded assembly 110 according to the present invention. FIG. 4schematically depicts a cross-section taken at line Y-Y through assembly110 of FIG. 3. T-316L stainless steel plate 112 is partially sandwichedbetween nickel cladding plates 114, which may be composed of, forexample, UNS N02201 nickel. The stainless steel plate 112 is subjectedto machining or another material removal process, or is cast or forged,so as to include a projecting marginal frame 116 on both sides ofstainless steel plate 112. The frame defines a recess having dimensionssuitable to receive a nickel plate 114. It will be understood that FIG.4 shows both nickel cladding plates 114 in place in recesses on opposedsurfaces of the stainless steel plate 112 that are defined by frame 116.Frame 116 is a projecting portion of the stainless steel plate 112 andframes the perimeter of each stainless steel plate 112. The seams,including seam 118, between the nickel plates 114 and the stainlesssteel frame 116 are welded using stainless steel filler wire. Thiswelded assembly design has the advantage that bar stock or other framingelements are unnecessary since the T-316L stainless steel core materialalso serves the function of the frame around the cladding material. Inaddition, the alternate design requires less welding than the design ofFIG. 2.

In the second step of the method of FIG. 1, the welded assembly isheated to high temperature and compressed by hot rolling to anintermediate gauge, thereby forming a hot rolled band or strip. Hotrolling causes the three plates in the welded assemblies shown in FIGS.2-4 to bond together at their interfaces. The welded assembly 10 of FIG.2, for example, may be heated to a suitably high temperature in air in astandard furnace, and then immediately rolled on a standard hot rollingmill used in steel production. In one embodiment, the heated assembly 10is rolled back and forth on a reversing mill until its temperature isreduced to a point that it can no longer be rolled in this manner. Ifnecessary, the compressed and elongated assembly 10 may then bere-heated to high temperature and again hot rolled on a reversing millto further reduce its gauge. A series of steps of re-heating and hotrolling may be employed until the thickness of the clad pack is reducedto a desired thickness or to a thickness suitable for cold rolling.

FIG. 5 is a schematic cross-sectional view taken at X-X through thewelded assembly 10 of FIG. 2 after hot rolling to a suitableintermediate gauge. Hot rolling compresses the stainless steel plate 12and nickel plates 14 of the welded assembly 10 to the thinner gaugestainless steel core layer 26 and nickel cladding layers 28 of theintermediate gauge product 20 shown in FIG. 5. In FIG. 5, stainlesssteel bar stock 16 has been compressed to thinner gauge stainless steelframing regions 30, with compressed weld regions 32 interposed betweenthe several layers. The interface of the stainless steel and nickelmaterials is shown as a dotted line in the schematic view of FIG. 5, aswell in FIGS. 6 and 7, described below.

FIG. 6 is a schematic cross-sectional view taken at Y-Y through thewelded assembly 110 of FIG. 3 after hot rolling to a suitableintermediate gauge. Hot rolling compresses the stainless steel plate 112and nickel plates 114 of the welded assembly 110 to the thinner gaugestainless steel core layer 126 and nickel cladding layers 128 of theintermediate gauge product 120 shown in FIG. 6. The frame 116 of thestainless steel plate 112 also has been compressed to a thinner gaugestainless steel framing region 130, with compressed weld regions 132interposed between the stainless steel framing region 130 and the nickelcladding layer 126 on both faces of the clad product.

The intermediate gauge clad materials shown in FIGS. 5 and 6, nowunitary pieces, can be trimmed to remove the edges, including thecompressed stainless steel framing regions 30, 130 and weld regions 32,132, respectively. FIG. 7 is a schematic cross-sectional view taken atX-X through the welded assembly 10 of FIG. 2 after hot rolling tointermediate gauge and after trimming at trim lines 40 shown in FIG. 5.Trimming leaves only the desired stainless steel core layer 26 andnickel cladding layers 28 bonded together. It will be apparent that thegeneral arrangement of elements in a transverse cross-section of theintermediate gauge product 120 once trimmed will be similar to thearrangement shown in FIG. 7.

Subsequent to trimming, the intermediate gauge product 20 of FIG. 7 maybe annealed in air or bright annealed to relieve stresses. The opposednickel surfaces 36 may then be blasted and pickled to remove oxide scaleand provide a surface condition suitable for cold rolling to finalgauge. If oxide scale is slight, it may be possible to pickle thematerial without blasting.

The third step of the method outlined in FIG. 1 involves reducing thethickness of the intermediate gauge product formed in a previous stepand, if desired, annealing to obtain desired metallurgical andmechanical properties. One or more cold rolling sequences is used,wherein each cold rolling sequence includes a step of cold rolling thematerial optionally followed by a step of annealing the material torelieve stresses and soften the material for the next cold rollingsequence. If the material is annealed in air during a particular coldrolling sequence, it may be necessary to pickle or blast and pickle thematerial to remove any oxide scale formed on it before the next coldrolling sequence. If, instead, the material is annealed during aparticular cold rolling sequence in an inert, non-oxidizing atmospheresuch as, for example, a hydrogen atmosphere, the oxide scale on thematerial may be negligible and require no blasting or pickling. Coldrolling sequences may be repeated until the material is reduced to thedesired final gauge. The clad material may be subjected to a finalanneal in hydrogen or another inert atmosphere to obtain desiredmechanical properties with a substantially oxide scale-free surface.

An end product formed using the method shown schematically in FIG. 1 isa sheet product comprising an alloy substrate (such as, for example, aT-316L stainless steel) clad on its opposed surfaces with a materialimparting desired corrosion resistance and/or other desired properties(such as, for example, nickel). FIG. 8 is a schematic cross-section of afinal product 40, wherein the core stainless steel layer 42 issandwiched between nickel cladding layers 44.

Although the above exemplary embodiments used to illustrate the methodshown in FIG. 1 are directed to producing dual-clad products, it will beunderstood that the method of claim 1 is equally useful for producingsingle-clad products, i.e., products clad on only a single face of thesubstrate material. It also will be understood that the variousschematic depictions of FIGS. 2-8 are provided only to better illustratecertain non-limiting embodiments of the methods of the presentdisclosure and may not depict the true relative dimensions of thevarious elements as would exist in a commercial-scale process. Forexample, it is likely that the cladding layer thickness would besignificantly thinner relative to the substrate layer thickness in anactual mill-scale process.

A significant advantage of the embodiment of FIG. 1 is that the methoddoes not require either the rolling of the assembled materials into atight coil or the use of a vacuum furnace to heat and bond the assembledmaterials as used in the prior art methods discussed in the backgroundsection above. Although the materials to be bonded must be heated tohigh temperature in the cladding method of the present disclosure, it isbelieved that the bonding of the material during the cladding processactually is more a result of the high interface pressure achieved duringrolling. The embodiment of FIG. 1 also does not require the use ofcomplicated and costly explosive bonding equipment to bond the variousmaterials.

Although the above description and the examples below either mention orinvolve the cladding of nickel on a stainless steel substrate, it willbe understood that the methods of the present disclosure are not solimited. It is believed that the method of FIG. 1 and, more generally,the novel method of the present disclosure may be adapted to produce awide variety of single-clad and multiple-clad alloy substrates. Also, asnoted above, the method of the present disclosure is particularly usefulfor producing clad products wherein the cladding material is of a lowerhot strength than the substrate material. When rolling stacked plates ofa high hot strength substrate material and a lower hot strength claddingmaterial, the lower hot strength material can tend to spread beyond thedimensions of higher hot strength material during hot rolling of theassembled materials. In such case, the higher hot strength materialprovided in the margin between adjacent edges of the cladding materialand the substrate material in the welded assembly of the method of thepresent disclosure, whether or not a part of the substrate material,inhibits spreading of the cladding material beyond the edge of thesubstrate material during hot rolling.

Generally, non-limiting examples of clad products that can be producedusing the method of the present invention include the following: cladplate, clad strip and clad sheet. The clad products may be furtherprocessed into various articles of manufacture. Also, although the abovedescriptions and the examples below are directed to double-cladproducts, wherein cladding layers are bonded to each of the opposedsurfaces of a substrate, the method of the present disclosure may beadapted to produce either single-clad and multiple-clad products, andsuch products may be further processed into articles of manufacture. Asnoted above, examples of articles of manufacture that may be made fromsingle-clad and/or double-clad products made using the method of thepresent disclosure include, but are not limited to, chemical cisterns,chimney flues, batteries, tubing, heat exchangers, piping for oil andgas, tanks for chemicals, and cookware. Other products and articles ofmanufacture that can be made using the method of the present disclosurewill be apparent to those having ordinary skill in the metallurgical andmanufacturing arts upon considering the present description and suchpersons may suitably adapt the method of the present disclosure withoutundue experimentation.

The absolute and relative dimensions of the various substrate, claddingand, if distinct from the substrate, framing elements assembled into awelded assembly in the method of the present disclosure are chosen toprovide a suitably dimensioned final clad product. Examples of certainnon-limiting embodiments of the present invention follow. The absoluteand relative dimensions of the various elements described in thefollowing examples were chosen for a particular application and reflectonly several non-limiting examples of specific embodiments of themethod. More generally, depending on the particular intended applicationof the clad product, any of a wide range of final clad productthicknesses and thickness ratios can be produced in a manner similar tothat used in the above description and the following examples. Aspectsinvestigated while carrying out the following examples includeinhibiting the cladding layer from flowing to an undesirable degreeduring hot rolling, suitably annealing the cladding and substrate layersduring cold rolling, preventing formation of excessive scale on thecladding layer surfaces during annealing, and the ability of blast andpickling practices to remove undesirable scale prior to assembling theelements of the welded assembly.

EXAMPLE 1

A welded assembly was prepared to produce a nickel double-clad stainlesssteel. The assembly comprised a 2 to 2½ inch thick T-316L stainlesssteel plate sandwiched between two ½ to ¾ inch thick nickel (UNS 02201)plates. The length and width dimensions of the nickel cover plates weresmaller than the stainless steel core plate, and the nickel plates werecentered on the faces of the stainless steel core plate. In this way, amargin was left around the perimeter of each face of the core plate thatwas not covered by the cover plate disposed on the face. A frameconstructed of ½×½ inch thick T-304 stainless steel bar stock waspositioned in the margin on each face of the core plate, around theperiphery of each of the cover plates. The stainless steel frame wasintended to “dam” the lower hot strength (and therefore more fluid)nickel during hot rolling and to inhibit or prevent the nickel materialfrom flowing beyond the edges of the core plate material as the entireassembly was reduced in thickness during hot rolling. The thicknesses ofthe individual plates were selected, in part, so that the rollingequipment available for the trial could accommodate the total assemblythickness.

The assembly was constructed and processed as follows. The two nickelcover plates were cut so that when the elements were assembled a ½ inchgap was left between their edges and the opposed edges of the T-304stainless steel frame elements. This is shown in the photograph of FIG.9, wherein the assembly 210 includes a nickel cover plate 212 disposedon T-316L stainless steel plate 214 between T-304 stainless steelframing elements 216, leaving a ½ inch gap 218 around the cover plate212. The ½ inch gap was provided to increase penetration of weld metalduring welding. Each of the framing elements 216 was MIG welded to thecore plate 214 at the exposed interface between those elements runningthe circumference of the assembly using 1/16 inch diameter ER308 weldingwire and 98% argon/2% oxygen shielding gas. The framing elements 216also were MIG welded to their respective adjacent cover plate 212 byfilling the ½ inch gaps between those elements using 3/32 inch diameterINCO 92™ ERNiCrFe-6 welding wire and 95% argon/5% hydrogen shieldinggas. The completed welded assembly 230 is shown in FIG. 10.

The welded assembly was heated to 2050° F. in a furnace and hot rolledfrom its original 3 inch thickness down to 0.401 inch. The assembly wasnot evacuated prior to hot rolling. Micrographs of a cross-section ofthe hot rolled assembly, shown in FIGS. 11( a) and (b), revealed thatboth of the nickel/T-316L stainless steel interfaces were completelybonded with a generally very clean interface. However, occasionalregions of the nickel/T-316L stainless steel interface includedsignificant entrapped oxide scale. It was unclear at the time whetherthe entrapped scale was embedded in the plate surfaces prior to hotrolling, was formed during hot rolling due to the presence of air in thewelded assembly, or was present due to a combination of both factors.

Two sections were cut from the hot rolled clad pack assembly andreheated, a first section to 2050° F. and the second section to 2200° F.Each reheated section was then hot rolled, the first section to 0.142inch and the second section to 0.125 inch. The hot rolled sections werethen trimmed to remove the framing material and weld deposits, so thatthe only material left was a nickel/T-316L stainless steel/nickellaminate. Metallographic inspection of the laminate revealed that alllayers remained well bonded.

Annealing studies discussed below indicated that an anneal at 1950° F.for 5 minutes was sufficient to soften the hot rolled sections forsubsequent cold rolling. Accordingly, a 3×14 inch piece of the 0.142inch thick hot rolled double-clad material, shown in FIG. 12, wasannealed at 1950° F. for five minutes, and then cold rolled to 0.013inch final gauge using the following cold rolling/annealing sequence:

Any single roll pass during cold rolling was limited to about 0.005 inchreduction so as to limit stresses and reduce the risk of delamination.No delamination or edge checking was observed during any of the coldrolling sequences. To condition the surface of the 0.013 inch finalgauge material, a blast and pickle operation may be used.

The percentage thickness of nickel cladding was measured for each stageof processing of the welded assembly in this Example 1 in order toevaluate how well the nickel remained contained within the T-304stainless steel framing, and also to determine whether the formation ofoxide scale consumed an excessive amount of the nickel cladding duringannealing. The nickel layer thickness remained fairly constant from itsoriginal amount (16.5 to 17% of total assembly thickness per side)through the third cold rolling/annealing cycle. The nickel claddinglayers became relatively thinner during the final cold rolling sequence,and the final gauge material had a nickel cladding layer thickness ofabout 15% of total clad product thickness per side.

To avoid the risk of distortion to the material surfaces during blastand pickling, bright annealing in hydrogen may be used in place ofannealing in air in the above cold rolling series and to provide thematerial with its final grain size and mechanical properties. Toevaluate the use of bright annealing, individual 1×1 inch specimens offinal gauge (0.013 inch) cold rolled material were bright annealed at1500° F., 1600° F. and 1700° F. for each of 1, 2 and 3 minutestime-at-temperature. The bright annealing appeared to provide anacceptable scale-free surface on the double-clad specimens.Metallography was performed in the bright annealed specimens todetermine what microstructure resulted from the nine temperature-timecombinations. The nickel layers on all nine specimens appearedmetallographically similar, with each layer being fully recrystallized,having noticeable grain growth, and a grain size of about 7½ to 8 usingthe ASTM Comparison Method. It was observed that only those specimensbright annealed to at least 1600° F. for at least 2 minutes were fullyrecrystallized. The fully recrystallized stainless steel core layers hada grain size of approximately ASTM 11, and the specimen bright annealedat 1700° F. for 3 minutes appeared to have the most homogenousmicrostructure. The average Vickers microhardness of the T-316L corelayer for the bright annealed specimens was 178.

Considering the foregoing bright annealing results, a 3×12 inch piece ofthe as-cold-rolled final gauge material from this example was brightannealed in hydrogen at 1700° F. for 3 minutes. Two tensile testspecimens were stamped from this material and the yield strength,ultimate tensile strength, and percent elongation were evaluated. Theaverage test values for these properties were 40.7 ksi, 86.6 ksi and48.7%, respectively.

EXAMPLE 2

A welded assembly constructed substantially the same as in Example 1 wasprepared. As in the assembly of Example 1, a ½ inch gap was left betweeneach of the nickel cover plate edges and the edges of the stainlesssteel framing material. In order to provide extra support against anylateral movement of the cover plates during rolling, but to still allowspace for the cladding material to flow, two short end dams weredesigned into the framing elements such that each included two ½ inchtabs that mate flush against the adjacent cover plate. This arrangementis shown in FIG. 13, which shows one surface of the assembly 310 inwhich nickel plate 312 and T-304 stainless steel framing elements 314,316 are positioned on T-316L stainless steel plate 318. Opposed framingelements 314 include tabs 320 flush with the adjacent cover plate 312.The nickel cover plates and framing elements 314, 316 were then weldedin place on the stainless steel core plate 318 in a manner similar tothe assembly of Example 1.

A surface of the welded assembly is shown in FIG. 14. The weldedassembly of this example was then heated to 2050° F. and hot rolled fromits original 3-inch thickness down to 0.400 inch. The assembly was notevacuated prior to hot rolling. Metallographic analysis performed on thehot rolled material showed the nickel/T-316L stainless steel interfaceto be similar to that produced with the welded assembly of Example 1,though one end of the hot rolled band included a shallow area ofdelamination between the nickel and stainless steel core material. Asection of the 0.400 inch piece was re-heated to 2050° F. and hot rolledto 0.143 inch.

An annealing study was performed on samples of the 0.143-inch hot rolledmaterial to investigate suitable temperatures and times for annealingthe hot rolled material prior to cold rolling. Five pairs of 2×3 inchsamples of the hot rolled material were annealed at 1950° F. for 2, 5,8, 14 and 20 minutes. The specimens annealed at 1950° F. for 5 minutesappeared to produce a fully recrystallized microstructure in both theT-316L core layer and nickel cladding layers without excessive graingrowth in the layers.

EXAMPLE 3

Observation of the assemblies of Examples 1 and 2 above indicated thatthe nickel cover plate material did not flow over the stainless steelframing and was fully contained within the framing during hot rollingreduction. Thus, the ½ inch gap between cover plates and the framingelements was eliminated in the assembly of this Example 3. It isbelieved that such design may provide a higher yield of double-cladmaterial since without the gaps the cover plate can cover a largerpercentage of the surface width of the core plate. FIG. 15 shows thewelded assembly 410 of Example 3 with the cover plate 412 welded to thebutted-up framing elements 416 and the framing elements 416 welded tothe core plate 414. As shown in FIG. 15, hydraulic tubing 420 was weldedto an evacuation bore in the side of the 2-inch thick core plate 414.The evacuation bore passed into the core plate 414 and intersected at aright angle with a bore drilled entirely through the core plate 414,opening at the two faces of the core plate 414 covered by the coverplates 412. As such, the evacuation bore and hydraulic tubing 420fluidly communicated with the spaces between the core plate 414 and thecover plates 412. Most of the air in the welded assembly 412 wasevacuated through tubing 420, and the evacuation bore in the assembly412 was then welded shut prior to hot rolling.

The evacuated welded assembly was hot rolled at 2050° F. to 0.402 inch,and subsequently re-heated to 2050° F. and hot rolled to 0.138 inch.Metallographic analysis was performed on the material at each thickness.The samples examined showed that the nickel/T-316L stainless steelinterfaces were completely bonded with no evidence of voids or largeoxide inclusions. The samples exhibited inclusions in an amount, sizes,and distribution very similar to what was seen in hot rolled samples ofthe welded assemblies of Examples 1 and 2. This indicated that theinclusions found at the core/cladding interfaces are not due to thepresence of air within the welded assemblies, but instead from scalepresent on the plates' contacting surfaces before construction of thewelded assembly. It therefore appears that it is unnecessary to evacuatethe welded assembly constructed according to embodiments of the methodof the present disclosure prior to hot rolling. It also follows thatpreparing the plates' surfaces by surface grinding and/or other surfacepreparation techniques to remove surface scale may be important. Ofcourse, the advantage gained from such surface preparation will dependon the composition and condition of the plates used, and certain plates,for example, may be composed of material more likely to developproblematic corrosion.

EXAMPLE 4

In view of the success of the cold rolling schedule used with the hotrolled material produced in Example 1, a more aggressive cold rollingschedule was tested on a welded assembly having a constructionsubstantially the same as in Example 1. It was observed that there wasno significant difference in the extent of oxide inclusions at thestainless steel core/nickel cladding interface in hot rolled productproduced from the evacuated and unevacuated assemblies of the aboveexamples. Thus, the clad pack assembly of Example 4 was not evacuated.

The welded assembly was hot rolled at 2050° F. to 0.401 inch, andsubsequently reheated to 2200° F. and hot rolled to 0.119 inch. Half ofthe 0.119 inch material (“assembly #4-A”) was annealed at 1950° F. for 5minutes to soften it for cold rolling. The remaining half of the 0.119inch material (“assembly #4-B”) was reheated to 2200° F. and hot rolledagain for two passes to reduce it to 0.085 inch. The reduced hot bandgauge relative to assembly #1A would allow for fewer coldrolling/annealing cycles to reach final gauge. Assembly #4-A wassuccessfully cold rolled to the desired final gauge of 0.013 inch usingthe following three cold rolling/annealing cycles:

The reduced hot rolled band gauge material of assembly #4-B wassuccessfully cold rolled to the desired final gauge of 0.01 inch usingjust two cold rolling/annealing cycles as follows:

Any single roll pass during cold rolling in the above two sequences waslimited to about 0.005 inch and about 5% reduction so as not to overlystress the material and risk delamination. Respecting these limitations,no delamination or edge checking was observed during any of the rollingsteps carried out on assemblies #4-A and #4-B, which indicates thatfairly aggressive cold rolling is possible. The final gauge materialfrom assemblies #4-A and #4-B was bright annealed in hydrogen at 1700°F. for 3 minutes, and tensile testing was performed in the brightannealed material. More aggressive cold rolling also was investigated,which can increase production speed. A specimen of annealed and pickled0.0119 inch hot band material from assembly #4-A was cold rolled asfollows:

The cold rolling was performed with an approximately 15% reduction inthickness per rolling pass, or about three times the targeted per-passthickness reduction limit as in the prior cold rolling sequences. Theresulting final gauge double-clad material exhibited no signs ofdelamination, though some edge roughness did occur. However, since thefinal gauge material would be edge trimmed to a desired width and toremove evidence of the framing material and weld deposits, the edgeroughness likely is insignificant. The metallurgical and mechanicalproperties of the 0.013 inch final gauge bright annealed, cold rolleddouble-clad material were as listed in Table 1.

TABLE 1 Property Average Test Result Nickel ratio 15.1% (per side)Nickel Thickness 0.0020 inch (per side) Grain Size ASTM 7 (Ni) ASTM 10(T-316L) Tensile Strength 83,900 psi Yield Strength 37,200 psi PercentElongation 46.2% Hardness 96 HV (Ni) 180 HV (T-316L) Bending Test 4 of 4bend tests→ no defects

EXAMPLE 5

A mill-scale welded assembly was constructed from a 3.75-inch thickT-316L stainless steel plate as core material having length of 132inches and width of 32.5 inches. The core plate was sandwiched betweentwo 0.75-inch thick UNS 02201 nickel plates having length of 128 inchesand width of 28.5 inches. The core plate was machined on both sides toprovide recessed regions to accept the nickel plates, which were ofsmaller length and width dimensions. As such, a margin of the T-316Lstainless steel plate encircled or “bordered” the periphery of thecladding material plates and thereby provided an integral frame toinhibit or prevent the nickel cladding material from spreading beyondthe dimensions of the stainless steel core material during hot rolling.The nickel plates were welded to the frame defined by the core materialgenerally as described in the examples above. The assembly was thenheated to 2050° F. and hot rolled to an intermediate gauge hot rolledband on a mill-scale hot strip mill.

Micrographs of samples from the hot rolled band were examined and showedthat the quality of the bonds between the core and cladding layers wasvery good. The band surface was inspected and found to be acceptable,with the only observed significant flaw being a blister in one locationnear the strip center. Some insignificant feathering/delamination wasobserved along the fusion border between the weld deposit and the nickelcladding layer. The hot rolled band was cold rolled, annealed andprepared for leveling.

EXAMPLE 6

A mill-scale welded assembly may be prepared from a 132 inch×32.5 inch(length×width) T-316L stainless steel plate as core material, and two128 inch×28.5 inch UNS 02001 nickel cover plates as cladding material.The thickness of the core plate may be 3.75 inches, and the thickness ofeach cover plate may be 0.75 inch, for a total assembly thickness 5.25inches. A recess shaped to accept a cover plate is machined in each faceof the core plate, with three pegs machined at each of the ends of eachrecess. FIG. 16 is a schematic top view of one face of the core plate220, showing the recess 224, the projecting margin 226 left on the coreplate 220 and defining walls of the recess 224, and the six pegs 225extending from the surface 227 of the recess 224. The remaining face ofthe core plate 220 (not shown in FIG. 16) will have a substantiallyidentical design. Each nickel cover plate is machined to include sixbores in predetermined positions, and each cover plate is positioned ina recess of the core plate so that the six pegs of the core plateproject through the six bores machined in the clover plate. Thethickness of the core plate may be 3.75 inches, and the thickness ofeach cover plate may be 0.75 inch, for a total assembly thickness 5.25inches. The cover plates are welded to the core plate at the seamsbetween the cover plates and the core plate's projecting margin, and atthe seams between the pegs and the bores in the cover plates. The pegsare provided to further inhibit slippage of the cover plates relative tothe core plate during hot rolling.

The assembly is heated to approximately 2050° F. and hot rolled on areversing mill to a hot rolled band of intermediate gauge. The hotrolled band may then be trimmed to a desired width suitable for coldrolling. The hot rolled band is then annealed in air, for example, at1900° F. for 1 minute time-at-temperature, descaled, optionally pickledand surface ground, and then cold rolled. The cold rolled material isthen annealed in air, for example, at 1900° F. for 1 minutetime-at-temperature, descaled, optionally repickled and surface ground,and rolled. This material is bright annealed, cold rolled to finalgauge, and then bright annealed once again. The material may then bestretcher leveled, if desired.

It will be understood that the present description illustrates thoseaspects relevant to a clear understanding of the invention. Certainaspects that would be apparent to those of ordinary skill in the art andthat, therefore, would not facilitate a better understanding of theinvention have not been presented in order to simplify the presentdescription. Although embodiments of the present invention have beendescribed, one of ordinary skill in the art will, upon considering theforegoing description, recognize that many modifications and variationsof the invention may be employed. All such variations and modificationsof the invention are intended to be covered by the foregoing descriptionand the following claims.

What is claimed is:
 1. A method for producing a clad product, the method comprising: providing a welded assembly comprising an alloy cladding material plate disposed on a steel plate, and an alloy material comprising a hot strength greater than the cladding material plate, wherein in the welded assembly at least a first edge of the cladding material plate does not extend to a first edge of the steel plate to define a margin therebetween, and wherein the alloy material is disposed in the margin and adjacent the first edge of the cladding material plate; and hot rolling the welded assembly to provide a hot rolled band, wherein the alloy material inhibits the cladding material plate from spreading beyond the edge of the steel plate during the hot rolling.
 2. The method of claim 1, wherein the cladding material plate is disposed in a recess on a surface of the steel plate such that a projecting portion of the steel plate defines at least one wall of the recess and is within the margin and adjacent at least the first edge of the cladding material plate.
 3. The method of claim 2, wherein the recess is provided in the surface of the steel plate by one of casting, forging, machining, and a material removal process.
 4. The method of claim 1, wherein the welded assembly is welded together completely around a seam between the entire peripheral edge of the cladding material plate and the projecting portion of the steel plate.
 5. The method of claim 1, wherein in the welded assembly a surface of the cladding material plate is substantially coplanar with a surface of the projecting portion of the steel plate.
 6. The method of claim 1, wherein the cladding material plate has a length and a width, respectively, that are less than a length and a width of the steel plate such that the margin extends around the entire periphery of the steel plate.
 7. The method of claim 1, wherein the cladding material plate has a length and a width, respectively, that are less than a length and a width of the steel plate, and wherein the projecting portion of the steel plate extends around the entire periphery of the steel plate to define the perimeter wall of the recess and is adjacent the entire peripheral edge of the cladding material plate.
 8. The method of claim 1, wherein at least one framing element of the alloy material is positioned on the steel plate within the margin and adjacent the first edge of the cladding material plate.
 9. The method of claim 1, wherein the cladding material plate has a length and a width, respectively, that are less than a length and a width of the steel plate, the margin surrounds the entire periphery of the cladding material plate, and one or more framing elements are positioned on the steel plate within the margin and adjacent the entire peripheral edge of the cladding material plate.
 10. The method of claim 1, wherein the steel plate is selected from the group consisting of stainless steel and carbon steel.
 11. The method of claim 1, wherein the steel plate is selected from the group consisting of T-316L stainless steel, T-316 stainless steel, T-304L stainless steel, and T-304 stainless steel.
 12. The method of claim 1, wherein the cladding material plate is selected from the group consisting of nickel, a nickel alloy, copper, a copper alloy, and a stainless steel.
 13. The method of claim 1, wherein the cladding material plate is selected from UNS N02200 nickel and UNS N02201 nickel
 14. The method of claim 1, wherein the alloy material is selected from the group consisting of stainless steel, a nickel-base superalloy, and a cobalt-base superalloy,
 15. The method of claim 1, wherein the alloy material is selected from the group consisting of T-316L stainless steel and T-304 stainless steel.
 16. The method of claim 1 further comprising: optionally annealing the hot rolled band; and cold rolling the hot rolled band to a clad strip having a desired gauge.
 17. The method of claim 16, wherein cold rolling the hot rolled band to a clad strip having a desired gauge comprises two or more steps of cold rolling, wherein the cold rolled strip is annealed intermediate successive steps of cold rolling.
 18. The method of claim 16, wherein the cold rolled strip is bright annealed intermediate at least two successive steps of cold rolling.
 19. The method of claim 1, wherein providing the welded assembly further comprises welding the alloy material to the cladding material plate and steel plate.
 20. The method of claim 1, wherein providing the welded assembly further comprises welding the portion of the steel plate in the margin to the cladding material plate.
 21. The method of claim 1, wherein the clad product is a dual-clad product and the welded assembly comprises two cladding material plates, one of the cladding material plates being disposed on each of the opposed surfaces of the steel plate.
 22. The method of claim 1, wherein the cladding material plate is nickel UNS N02201 nickel, the steel plate is T-316L stainless steel, and the alloy material is selected from T-316L stainless steel and T-304 stainless steel.
 23. A method for producing a clad stainless steel, the method comprising: providing a welded assembly comprising disposing an alloy cladding material plate on a stainless steel plate, wherein at least a first edge of the cladding material plate does not extend to a first edge of the stainless steel plate and thereby provides a margin on the stainless steel plate, disposing at least one framing element within the margin and adjacent the first edge, wherein the framing element is an alloy having greater hot strength than the cladding material plate, welding the cladding material plate to the framing element, and welding the framing element to the stainless steel plate; and hot rolling the welded assembly to provide a hot rolled band, wherein the framing element inhibits the cladding material plate from spreading beyond the first edge of the stainless steel plate during the hot rolling.
 24. The method of claim 23, wherein the cladding material plate has a length and a width, respectively, that are less than a length and a width of the stainless steel plate and each edge of the cladding material plate is spaced from the adjacent edge of the stainless steel plate so that a margin extends around the entire periphery of the stainless steel plate, and further wherein one or more framing elements are disposed in the margin around the entire periphery of the cladding material plate.
 25. The method of claim 23, wherein the stainless steel plate is selected from T-316L stainless steel, T-316 stainless steel, T-304L stainless steel, and T-304 stainless steel.
 26. The method of claim 23, wherein the cladding material is selected from the group consisting of nickel, a nickel alloy, copper, a copper alloy, and a stainless steel.
 27. The method of claim 23, wherein the one or more framing elements are selected from the group consisting of stainless steel, a nickel-base superalloy, and a cobalt-base superalloy.
 28. The method of claim 31, wherein the cladding material plate is nickel, the stainless steel plate is T-316L stainless steel, and the one or more framing elements are one of T-316L stainless steel and T-304 stainless steel.
 29. The method of claim 23, wherein the clad product is a dual clad product, and providing the welded assembly comprises: disposing an alloy cladding material plate on each of the opposed surfaces of a stainless steel plate, wherein at least a first edge of each of the cladding material plates does not extend to a first edge of the stainless steel plate and thereby provides a margin on each of the opposed surfaces of the stainless steel plate; disposing at least one framing element in the margin and adjacent the first edge of each cladding material plate, wherein the at least one framing element comprises an alloy having hot strength greater than the cladding material plate; and welding each cladding material plate and the stainless steel plate to the adjacent framing element.
 30. The method of claim 29, wherein each cladding material plate has a length and a width, respectively, that are less than a length and a width of the stainless steel plate and are disposed on the stainless steel plate such that the margin extends around the entire periphery of the stainless steel plate on each opposed face of the stainless steel plate, and wherein one or more framing elements is disposed in the margin around the entire periphery of each cladding material plate.
 31. The method of claim 23 further comprising: optionally annealing the hot rolled band; and cold rolling the hot rolled band to a clad strip having a desired gauge.
 32. A method of making an article of manufacture, the method comprising: making a clad product by the method of any of claims 1 and 23; and fabricating the clad product into the article of manufacture.
 33. The method of claim 32 wherein the article of manufacture is selected from the group consisting of a cistern, a chimney flue, a battery, tubing, a heat exchanger, a pipe, a tank, and an item of cookware.
 34. A welded assembly useful in the production of clad products, the welded assembly comprising an alloy cladding material plate disposed on a steel plate, wherein in the welded assembly at least a first edge of the cladding material plate does not extend to a first edge of the steel plate and thereby provides a margin between the first edges, and wherein an alloy material is within the margin and adjacent the first edge of the cladding material, wherein the alloy material has hot strength greater than the cladding material.
 35. A welded assembly useful for producing a clad product, the welded assembly comprising: a stainless steel plate having a first edge; an alloy cladding material plate having a first edge, wherein the cladding material plate is disposed on a surface of the stainless steel plate, and wherein the first edge of the cladding material plate does not extend to the first edge of the stainless steel plate and thereby provides a margin on the stainless steel plate between the first edges; and a framing element within the margin and adjacent the first edge of the cladding material plate, wherein the framing element is an alloy having hot strength greater than the cladding material plate, and wherein the framing element is welded to the stainless steel plate and the cladding material plate. 